(iv) Tribimaximal mixing: The mixing matrix (REF ) has a
structure that is consistent with the following unitary matrix
[1]}:
\(U=\begin{pmatrix}\sqrt{\frac{2}{3}}&\sqrt{\frac{1}{3}}&0\\-\sqrt{\frac{1}{6}}&\sqrt{\frac{1}{3}}&\sqrt{\frac{1}{2}}\\\sqrt{\frac{1}{6}}&-\sqrt{\frac{1}{3}}&\sqrt{\frac{1}{2}}\end{pmatrix}.\) 
